Controlling device for the main clutch in motor vehicles



K. MAYBACH H,999,366 -CONTROLLING DEVICE FOR THE MAIN` CLUTCH IN MOTORVEHICLES 3 Sheets-Sheet l Filed Jam.4 24, 1953 pril 30, 1935. K, MAYBACH1,999,366

CONTROLLING DEVICE FOR THE MAIN CLUTCH IN MOTOR VEHICLES FiledA Jan. 24,1935 3 Sheets-Sheet 2 April 3o, 192.5.- K. MAY-BACH 1,999,366-

f CONTROLLING DEVICE FOR THE MAIN CLUTCH IN MOTOR VEHICLES Filed Jan.24, 1955 s s\"1"`etssheet s fig 4.

Patented 'Apr. 30, 1935 UNITED STATES PATENT OFFICE CONTROLLING DEVICEFOR. THE MAIN CLUTCH 1N MOTOR VEHICLES Application January Z4, 1933,Serial No. 653,259 In Germany February 12, 1932 1 Claim.

My invention relates to clutches in motor vehicles and has specialreference to the main clutch usually arranged between the motor and thechange speed gear in motor cars and the like.

Generally such a clutch is operated by means of a lever, preferably afoot lever, which acts against a spring. It has already been suggestedto provide in addition means for declutching during a certain timeperiod so as to allow freewheeling of the vehicle, these additionalmeans being in no direct connection with the usual foot lever foroperating the clutch. They may be made up of mechanical members such asrods, levers and the like, also electrical elements may be provided l'orsuch purpose, but mostly pressure means, such as a liquid, pressure gasor vacuum are made use of.

In this latter case it is preferred to provide a pressure control memberto be operated at will by the driver and to have the pressure or vacuumact on a piston in a cylinder or on a diaphragm, which in turn causedeclutching and reclutching. The arrangement may also be made so thatwhen shutting off the gas supply to the motor, which generally meanstaking therfoot from the gas pedal, automatically the pressure controlmember is actuated thus causing de-clutching of the clutch. When thepedal is pressed down again the clutch automatically re-engages.

In arrangements of this latter kind it is usual to provide an additionalmember by which the automatically working free-wheeling means can beshut oif at the will of the driver.

All these arrangements in which the clutch is more or less automaticallyoperated have the great disadvantage that the engagement of the twoclutch elements is not under the Vcontrol of the driver and his feeling.Consequently shocks of heavier or feebler kind are unavoidable, even ifthe gas is given carefully and even if special means are provided forthe purpose of having a smooth engagement. Such shocks are disagreeablefor the people riding in the car and besides they lead to an increasedwear of the clutch elements.

According to my invention I avoid such draw- -backs by providing anadditional device which acts so on the clutch elements to be engagedthat their automatic engagement is prevented until these elements rotateat substantially equal speed of rotation. For this purpose I have a rstmember rotating in dependency of one of the two clutch elements and asecond member which rotates in dependency of the second clutch element,

and both members together influence a control member in such manner thatthis control member allows for engagement only after the two rotatingmembers have come to substantially equal speed of rotation. Suchrotating member may be for examplecentrifugal speed-responsive devicesor the like. If two devices of this kind act against each other orparallel to each other there will be a certain middle position in whichthe control member on which they act for instance causes an aperture tobe opened so as to allow for pressure or vacuum to pass and to lea-vethe clutch elements free for engagement.

, I prefer to provide liquid pressure pumps as primary members, one ofwhich is driven by one of the clutch elements whereas the other pumprotates in dependency of the other clutch element. These pumps are to beof practically equal efficiency and are arranged in series so that oneof them sucks out of the pressure space of the other. The pressureprevailing in this pressure space acts on the control member so thatwhen the pressure vanishes (with substantially equal speed of rotationof the pumps) the control member allows the clutch elements to engage.

There are other objects of my invention but al1 will be understood bestwhen having reference to the drawings which represent an exampleembodying my invention.

Fig. 1 is a diagrammatical longitudinal section 30 through the frictionclutch of a motor car and through the adjacent component parts of theentire arrangement, showing the clutch in released position.

Fig. 2 shows the main elements of Fig. 1 but 35 in diierent positions,also diagrammatically in section as in Fig. 1.

In Fig. 3 a third position is represented, and Fig. 4 shows anadditional device incorporated in exactly the same manner.

The gas lever la with pedal I in its rest position is held by means ofspring 2 against a support or bracket 3. lThe clutch pedal 4 with itslever 4a and arm 4b is adapted to press against .clutch element 'Isplined to shaft 6 which leads to the gear .45 box and to the wheels ofthe car. The fly-wheel 5 of the motor M which is only intimated on thedrawing forms the second clutch member adapted to engage with element 'Iunder the pressure of spring 8 when the pedal 4 is released.

There is a piston Il under the pressure of a spring rI2 in a cylinderIl' adapted to cause declutching by means of pistonv rod I0, link 4l)and the -continuation 9 of lever I whenever piston ll is moved to theright, for instance by vacuum 55 introduced by tube 36 and having itssource in the motor intake at I3. If this vacuum is turned on", as shownin Fig. 2, spring` I2 pushes piston I I into its left hand position sothat clutch spring 8 now is free to causel engagement of clutch elements5 and 1.

The tube I4 coming from the intake I3 leads to piston valve I6 which inits right hand position as shown in Fig. 1 causes connection to tube 32.This right hand position of piston valve I6 is caused by the position ofgas pedal I by means .of link I1 against the pressure of spring I8 whichtends to move valve I6 to the left.

Tube I4 has a branch tube I5 leading to a second piston valve I9 whichgenerally is pressed to the left by means of spring 20 which surroundsspring I8 and presses on piston 31 abutting valve I9. But the liquidpressure existing in the space 21 intermediate pump 2I driven by the`motor side of the clutch and pump 26 driven by shaft 6 to which clutchelement 1 is splined acts on valve I9 -against the action of spring 20.Thefpumps 2I and 26 are driven by flexible shafts 22 and 30,respectively, in any well-known manner, for instance by means of worms25 and 29 and Worm gears 24 and 28, respectively. The casing 3Isurrounds the pumps 2I and 26 and contains a liquid, as oil or thelike.4

Tube 32 connects to a control valve 33 adapted to be operated by footpressure against'the action of spring 35 and to allowvfor connection oftube 36 with tube 32 coming from valve I6 or with tube 34 coming fromvalve I9. If the valve 33 is pressed down tubes 32 and 36 are connectedand the vacuum in cylinder II' is consequently controlled by valve I6,whereas when valve 33 is in its upper position tubes 34 and 36 areconnected so that the vacuum in cylinder I I is controlled by valve I9.

In spite of all these valves and connections the driver may at leisuredisengage the clutch by means of the clutch pedal 4, because the slit inlink 40 provides for such movement independently from the' movement ofpiston II.

The operation of the mechanism is as follows:

When driving the driver normally has his left foot on the knob of valve33 thereby causing connection between tubes 32 and 36. His right foot ison the gas pedal I, as indicated in Figure 2. 1f from this state thedriver releases the gas pedal the link I1 during the last part of themovement of lever IEL draws valve I6 into its lright hand position, asshown in Fig. 1. Consequently the vacuum created in the intake I3 isconnected to the'right hand side of cylinder I I' by means of tubes I4,32 and 36, causing piston II to move to the right against the pressureof spring I2 and thereby disengaging clutch 5, 1 by means of rod I0,link 40 and lever 9.

The clutch remains disengaged until the gives gas again by depressingpedal I.

During the period the clutch 5, 1 had been engaged the two pumps.2I and26 driven by the motor shaft and by shaft 6, respectively, had equalspeed of rotation. Therefore, there was no pressure in the intermediatespace 21 and valve I9 was held in its left hand position by spring 20.When the clutch 5, 1 is disengaged by releasing'the gas pedal I themotor will slow down to its normal idling speed and pump 2| whichdepends on the motor speed will slow down also. The car moves on anddoes not lose in speed in the same degree as the motor. Consequently,pump 26 pumps more liquid than pump 2I is able to pump, which means thata certain driver pressure is created within space 21 pressing valve I9into its right hand position, as indicated in Fig. l. The piston 31prevents valve I6 from moving to the left even during the first periodof acceleration when lever Ia is pressed down, but with increasing motorspeed pump 2I pumps more and more of the liquid pressed into space 21 bypump 26 and as soon as the pumps are on equal speed again or a shortmoment later the pressure within space 21 vanishes and spring 20 pressesvalve I9 back into its left hand position. Valve I6 under the pressureof spring I8 follows this movement, so that both valves are in theposition shown in Fig. 2, in which tube I4 is shut oi by valve I6 andtube 32 is connected to aperture 38. Consequently, the vacuum in theright hand side of cylinder II vanishes through tubes 36, 32 andaperture 38 and piston I I by means of spring I2 is moved into its lefthand position and causes re-engagement of clutch 5, 1 over rod I0, link40 and lever 9, spring 8 constantly tending towards such engagement.

If the driver having removed his right foot.

from the accelerator removes his left foot (l) from the knob of valve33, which means that he .wants to stop free-wheeling and to have drivingconnection with the motor again, the engagement of the clutch 5, 1 isnot caused immediately but only after the two clutch elements 5 and 1have come to substantially equal speed of rotation.

In case the left foot (l) be removed while the other foot (r) is stillpressing down gas lever I,

this would not mean any influence on clutch 5, 1

because the only alteration would be (Fig. 2) that tube 36 would beconnected to tube 34 instead of to tube 32, both tubes being inconnection with the open air by means of apertures 39 and 38,respectively, and in both cases the clutch would remain engaged. And iffoot (l) is removed while pedal I is released also (Fig. 2), then itcomes to the conditions' represented in Fig. 3: Tube 36 is againconnected to tube 34 instead of to tube 32 and as now tube 34, becauseof valve I9 being in its right hand position, connects to the intake I3over tube I5 the vacuum causes the clutch 5, 1 to remain disengageduntil operation of gas lever Ia speeds the motor up so that both clutchelements 5 and 1 come to substantially equal speed, when they engage.

A very important additional device according to my invention is'shown inFig. 4. It is a piston 46 in a cylinder 45 which is under the action oispring 48 and the re-action of vacuum coming through tube 44 fromcontrol member 33. Piston rod 41 is adapted to press against arm I offoot lever I, so that this foot lever is depressed whenever the controlvalve 33 is released, because then tubes 34 and 44 are in connection.But as the vacuum in tube 34 depends on the position of valve I9 therewill be vacuum only as '-.ong as there is liquid pressure in space 21(that is during diierent speed of rotation of the pumps). Consequentlythe gas pedal will be depressed automatically whenever the driver lWantsto abandon the free-Wheeling state of the car (release of control valve33) so that the motor increases in speed untilbecauseof equal speed ofrotation the vacuum vanishes in cylinders II and 45, respectively, whichmeans that the clutch elements 5 and 1 engage and that the automaticinfluence on arm I' of the gas pedal ceases. Thus this new device is anautomatically working accelerator which acts whenever the driver returnsfrom .free-wheeling to ordinary circumstances. This is of greatadvantage in driving a motor car especially when going down a slope infree-wheeling state and suddenly discovering that the slope becomessteeper, so that the driver intends to come back to ordinary drivingconditions. In such case he has to do nothing but to release the controlvalve 33 and automatically the motor isv raised in revolutions until theclutch elements rotate substantially at equal speed so that againautomatically the clutch engages.

It may be advisable to make the arrangement` so that the two pumpsdiffer a little in their emciency in such manner that the pressure inspace 21 vanishes shortly before the clutch elementshave come to equalspeed of rotation so as to provide for retarding moments in the functionof the entire mechanism.

I do not want to be limited to the details'described or shown in thedrawings as' many variations will occur to thoseskilled in the art.

What I claim is:

In a motor vehicle in combination, a motor, a propeller shaft adapted tobe driven by said motor; a clutch inserted between said motor and saidpropeller shaft; said clutch having an element in driving connectionwith said motor and an element in driving connection with said propellershaft; a member for controlling the fuel admission to said motor;pressure means for engaging and disengaging said lclutch forfreewheeling purposes; two rotatable members, one in operativeconnection with the motor, the other one in operative connection withthe propeller shaft; a first control member for said pressure means,operating in dependency on both said rotatable members, adapted toprevent engagement of said clutch as long as its elements rotate atsubstantially different speeds; a second control member for saidpressure means, operating under the influence of said fuel controlmember and under the influence of said first pressure control member andbeing adapted to cause disengagement of said clutch when the fueladmission is shut off; and a third control member for said pressuremeans to be operatedat will and adapted to shut oi alternately one ofsaid first two pressure control members.

KARL MAYBACH.

